Changes in Stockholders' Equity and Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 01, 2017	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 270,430
Net loss for the three months ended April 1, 2017		$ (7,275)
Unrealized loss related to marketable securities, net of tax	(43)
Recognized loss on redemption of marketable securities, previously unrealized	170
Translation adjustments, net of tax	274
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax	451
Stock-based compensation expense related to stock options, ESPP and RSUs	3,843
Accounting method transition adjustment	(355)
Ending balance	267,495	270,430
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,216
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax	4
Ending balance	1,220	1,216
Additional Paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	680,315
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax	447
Stock-based compensation expense related to stock options, ESPP and RSUs	3,843
Ending balance	684,605	680,315
Accumulated deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(406,945)
Net loss for the three months ended April 1, 2017		(7,275)
Accounting method transition adjustment	(355)
Ending balance	(414,575)	(406,945)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(4,156)
Unrealized loss related to marketable securities, net of tax	(43)
Recognized loss on redemption of marketable securities, previously unrealized	170
Translation adjustments, net of tax	274
Ending balance	$ (3,755)	$ (4,156)